dougjk
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 p.1 #3 · Astrophotography Barn Doors | |
I've been considering making one of these. There's quite a lot of DIY info online, just google for barn door tracker. The simplest versions use just two planks, a piano hinge, and a manually turned threaded rod. They aren't accurate enough for long exposures, but for long exposures you need very accurate polar alignment anyway, and I'm thinking it makes more sense to start with a simple mount and just stack exposures.
When you start looking, you'll see talk of "tangent drive", "isosceles drive", and "dual arm" versions. These have increasing accuracy assuming a constant drive rate. Note that you can simply vary the drive rate to get perfect theoretical accuracy out of even the simplest version, so there's no reason to go with the more complex models unless you're going to put in a constant rate stepper motor to drive it.
I don't know of any commercially available versions.
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